Vacuum Actuated Resonator for Variable Engine Noise
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Solution Overview
Problem
Existing noise attenuation systems in vehicles, such as mufflers and resonators, are ineffective at varying frequencies and require additional packaging space, while active noise cancellation systems are costly and prone to heat and corrosion issues.
Innovation Solution
A noise attenuation device using a quarter-wave tube with selectively varying effective length through a vacuum-actuated valve system, allowing for passive adjustment of noise attenuation frequencies without additional packaging or active control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed geometry resonator is used, then noise attenuation is achieved at a specific frequency, but the resonator becomes ineffective at other engine speeds and frequencies
Solution Approach 1:
The patent applies the dynamics principle by making the resonator geometry variable through a vacuum-actuated valve system. The valve selectively opens or closes to change the effective length of the resonator tube, allowing the same physical resonator to adapt to different engine speeds and frequency requirements. This transforms a static resonator into a dynamic one that can maintain effectiveness across varying operating conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the effective length parameter of the resonator tube through vacuum actuation. By changing the length parameter in response to engine speed variations, the resonator maintains its noise attenuation effectiveness across different frequencies without requiring multiple fixed resonators.
2Adaptability or versatility
If multiple resonators are used to address different frequencies, then broader frequency coverage is achieved, but additional packaging room is required within the vehicle
Solution Approach 1:
The patent applies universality by designing a single resonator system that can perform multiple functions across different frequency ranges. Through vacuum actuation, one resonator tube can effectively cover the frequency ranges that would traditionally require multiple separate resonators, eliminating the need for additional packaging space while maintaining broad frequency coverage.
Solution Approach 2:
The patent merges the functionality of multiple frequency-specific resonators into a single variable-geometry resonator. By combining different length configurations into one physical tube with vacuum actuation, the system achieves the frequency coverage of multiple resonators while occupying the space of only one.
3Measurement precision
If active noise cancellation systems are used, then noise cancellation across frequencies is achieved, but the systems are costly and require positioning space within the cab
Solution Approach 1:
The patent replaces expensive active electronic noise cancellation systems with a simpler, passive acoustic resonator system. While the resonator itself is not disposable, the approach uses passive acoustic principles rather than expensive active electronics, microphones, speakers, and control systems, significantly reducing cost and complexity while maintaining noise cancellation effectiveness.
Solution Approach 2:
The resonator system is self-regulating through vacuum actuation that automatically adjusts the effective length in response to engine operating conditions. This eliminates the need for external electronic control systems, sensors, and power sources required by active noise cancellation systems, reducing both cost and complexity.
4Adaptability or versatility
If sound deadening material is used in mufflers, then broad range higher frequency dampening is achieved, but the material only dampens sounds over a broad narrow of higher frequencies and does not address lower frequencies effectively
Solution Approach 1:
The patent replaces passive sound deadening material with an active acoustic resonator system. Instead of relying on material absorption that is frequency-limited, the resonator uses acoustic wave generation and interference principles to actively counteract noise at specific frequencies, providing more precise and effective attenuation across both lower and higher frequency ranges.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively attenuates noise across a range of frequencies with a single quarter-wave tube unit, reducing the need for multiple resonators and minimizing packaging space, while avoiding the drawbacks of active systems.
Implementation Method 1
A noise attenuation device using a quarter-wave tube with selectively varying effective length through a vacuum-actuated valve system
Implementation Method 2
Another proposed solution for addressing undesirable noise is use of a Helmholz resonator or a quarter-wave resonator. These resonators produce a pressure wave that counteracts primary engine order noise waves.
Data Source
AI summary
A variable noise attenuation element includes at least two tube sections that define an overall tube length that defines a first effective length and associated first peak frequency for noise attenuation, and a valve having a valve member. The valve joins the tube sections together and includes openings that permit communication between the tube sections when the valve is in an open configuration. The valve member operates to close the opening in response to a predetermined vacuum level within the tube sections to define a second tube effective length and associated second peak frequency for attenuation that is less than the overall length. A method of attenuating noise in a vehicle using a passive attenuation arrangement operates a valve disposed between two tube sections to change an effective length of the tube and associated peak frequencies for attenuation in response to an engine operating parameter.